One common theme is identity struggle. Since Percy is known as Poseidon's son in the original lore, being the son of Gaea in fanfic is a huge shift. He has to figure out who he really is. Another theme is power. With Gaea as his mother, he might have different powers, and how he uses or controls them is often explored.
There's a fanfic called 'Percy, Son of Gaea: The Rebellion'. In this story, Percy discovers his true parentage and has to fight against the traditional demigod beliefs. It has some really cool battle scenes and character development. Also, 'Percy and Gaea's Bond' is a fanfic that focuses on the emotional aspect of Percy's relationship with Gaea, showing how he struggles to accept this new identity.
In a fanfic, Percy could have a mental battle with Gaea where the lemon plays a key role. Imagine Percy enters Gaea's mind - realm. There, he finds a withered lemon tree. By using his willpower and connection to the ocean (as water is also related to life like the lemon), he tries to revive the tree. As he does this, Gaea is forced to watch and is affected by his actions. If he succeeds in making the tree bloom again, it could signify his victory over Gaea's destructive plans.
One common theme is identity struggle. Since Percy is known as the son of Poseidon in the original, being the son of Gaea in fanfiction makes him question who he really is. Another theme is power and its consequences. With a different origin, he has different powers and has to deal with how they affect him and those around him.
This is a really interesting concept. In the original Percy Jackson series, Percy is the son of Poseidon. But in this fanfiction idea, if he were the son of Gaea and Tartarus, it would completely change his character and the story. His powers would likely be much darker and more primal. He might have an in - depth connection to the earth and the abyss, which could lead to some really unique storylines.
Yes, there are quite a few. You can start by looking on fanfiction websites like Archive of Our Own or FanFiction.net. Some might explore Percy's unique heritage as the son of both Gaea and Poseidon and how it affects his relationships with other characters in the Percy Jackson universe, like his friends at Camp Half - Blood or his enemies.
Gaea herself would obviously be a main antagonist. She has the power to manipulate the earth and all its forces against Percy. Her children who are fully committed to her cause could also be major antagonists. They might have powers related to the earth and be very difficult for Percy to defeat.
One possible plot could be Percy's discovery of his true parentage. He might struggle with the implications of being the son of two powerful primordial deities. For example, he could face a conflict between the forces associated with Ouranos and Gaea. This could lead to him having to make difficult choices about which side to support, if any. And he may also have to deal with the reactions of his friends and the other demigods who might view him differently now.
One possible plot could be Percy discovering his true parentage as Gaea's eldest son and struggling with the implications. He might have to face the wrath of the other demigods who see Gaea as an enemy. For example, he could try to convince his friends like Annabeth that he is still on their side despite his newfound origin.
Well, there's 'Percy Son of Gaea: A New Path'. In this fanfiction, Percy has to face a lot of challenges that are different from the original series as he is now the son of Gaea. It shows his struggle to find his place in a world that sees him as a threat at first. And 'Percy's Gaea - Bound Destiny' is also quite good, with a detailed exploration of how Percy's relationship with Gaea could change his relationships with his friends.